Additional thoughts
Nick is correct, the metal bowl unscrews from the top mounting and drops down. There is a 16mm bolt head cast into the middle of the bottom of the bowl that will do the trick. There is a shaft that runs up the middle of the filter and screws into the inside of the round stud on the top of the top mounting. Once you get the metal bowl off, the filter element just pulls out. There is an o-ring that you have to replace on the bottom of the paper filter element and then the whole thing just snaps down into the metal bowl. There is a rubber sealing gasket inside and around the edge of the top mounting that you will also have to replace. You can dig it out with a pick and a mirror helps to see what you are doing. When you put in the new rubber gasket, make sure that it is not twisted or you will have leaks. Once everything is in place, you can open the 10mm bleed screw on the top of the filter body and let all the bubbles out. It will help if put some grease or anti-seize on the threads at the top of the metal shaft and don't tighten too much. That way, it will be easier to get the thing apart next year